The performance of systems used to identify volatile compounds has been enhanced substantially thanks to research conducted under the Essaim project. Improvements were made to both the sensors and the data acquisition and processing methods.

Functionalized surface acoustic wave (SAW) sensors identify volatile compounds by detecting variations in the resonance frequency the compounds generate when they are adsorbed at the sensors' surface. In research conducted under the Essaim project, List, a CEA Tech institute, developed new SAW sensors and a multi-sensor method capable of obtaining a more specific "signature" than conventional SAW approaches.

Until now, organic compounds have been identified solely based on variations in the sensors' resonance frequency. The new method uses a representation of the data based on the equations that govern the sensors' physical parameters. The method, which is more complex, makes it possible to acquire more accurate variables. The characteristics extracted using the method resulted in classification rates in excess of 96% on test databases—an improvement of more than 7% in some cases. The new method can identify compounds and determine how many compounds are in a mix to generate a concentration profile.

The method could be of use for a variety of applications, from detecting toxic chemicals to controlling the quality of food. It was tested on different types of coffee with a success rate of 75%, compared to 62% previously in the best cases. The software is fully automated, making it usable even by non-specialists. All of these improvements have been integrated into PACT.